Conventionally, there has been a treatment method for replacing a natural tooth that is lost from tooth decay, periodontal disease or the like with an artificial tooth. Such a treatment method is called an implant treatment, which is a method where an artificial root of a tooth is embedded in a jawbone and an artificial tooth is secured onto the artificial root of the tooth to restore the appearance and functions that are no different from those of the natural tooth.
FIG. 38 is a diagram for explaining a common dental implant that is used as an artificial teeth in such an implant treatment. FIGS. 38(a) and 38(b) are a perspective view and a cross-sectional view that illustrate an implanted state of a dental implant embedded in a jawbone. FIG. 38(c) is an exploded perspective view of a dental implant.
A dental implant 10 comprises, for example, a cylindrical implant body (hereinafter, referred to as a fixture) 2 that is implanted into a jawbone (alveolar bone) 20 as an artificial root of a tooth, a support mount (hereinafter, referred to as an abutment) 3 that is secured to the head of the fixture 2, and a top structure 1 that is mounted onto the abutment 3 as an artificial tooth with an adhesive or a screw. The top structure 1 is called a restoration or a prosthetic crown, and the top structure 1 will also be referred to as a restoration hereinafter.
Here, the fixture 2 and the abutment 3 are connected by a threaded engagement so that they can be detached for cleaning between the abutment 3 and gums 21 or for replacing the abutment. That is, a female screw section (screw hole) 2a1 for threadedly engaging a male screw section 3a, which is formed at the lower portion of the abutment 3, is formed on a head 2a of the fixture 2.
Patent Literature 1 discloses the structure of the common implant explained in FIG. 38.